1. Field of Invention
The present invention relates to conveyor drive spreaders and, more specifically, to spreaders having a spinner and conveyor powered by separate motors.
2. Description of Prior Art
Conventional drive systems for a material spreading system on a vehicle, such as a hopper spreader, include an auxiliary source for powering both the conveyor drive system and the associated spreading spinner system. The auxiliary source may be a separate internal combustion engine, a hydraulic system with pump, valves and reservoir powered by the truck's engine, or an electric motor that is powered by the electrical system of the vehicle. Electrically powered spreaders are advantageous because they eliminate the need for a separate high maintenance auxiliary engine to power the spreader or the expense of attaching a separate hydraulic system to power the spreader hydraulically.
Conventional electrically powered spreaders were developed from engine-driven or truck-powered hydraulic spreaders. As auxiliary engine driven spreaders and hydraulically powered spreaders had an abundance of power, the low efficiency of the spreader's gear drive system did not affect the operational performance of these two types of spreaders. These spreaders could move the conveyor fast enough to spread effectively at faster speeds of up to 30 MPH that are required when operating this type of spreader.
When the electric spreader was developed, the low efficiency (30%) conveyor drive system of the hydraulic and engine drive spreaders resulted in a conveyor that ran very slow on the minimal amount of truck amperage that was available. The conveyor of the conventional electric spreader does not run fast enough to unload a sufficient amount of material at the higher speeds required in many spreading applications. These slow, electric spreaders are known as “walking speed” spreaders, and cannot be used in faster applications that a separate engine or hydraulic system powered spreaders can handle.
Another disadvantage of the conventional electric spreaders is that the single electric motor draws so much of the truck's amperage that it becomes impractical to power a separate electric motor to run the spinner disc. In hydraulically powered spreaders, independent control of conveyor and spinner was available gives the operator the flexibility in spreading operation to adjust to changing weather, traffic patterns or obstacles. Powering a second electric motor while the first motor is using most of the available amperage drains the battery system on the truck rather quickly. As a result, the conventional electric spreader is generally powered by just one electric motor, and thus is incapable of giving the user independent control over the conveyor and spinner disc.